There were certainly some issues early on (the thing with list MPs leaving their party but keeping their seat, for example) but I think those have been ironed out now?

I feel like maybe there is too much power given to kingmakers, like the anti-smacking bill for example - the vast majority of the population didn't want it, neither National nor Labour really wanted it, but it got rammed through by the Greens because Labour needed their support to govern. But overall, I think it's still better than the arrangement here (the UK) where the Lib Dems got piles of popular support at the last election but retained relatively little power from it.